Device for measuring the elasticity of red blood corpuscles (erythrocytes)

ABSTRACT

When injecting red blood corpuscles it is important to know their elasticity since they can alter from an elastic to a substantially rigid state. The present invention allows it to be ascertained whether the elasticity fulfills the requirements stipulated.

BACKGROUND OF THE INVENTION

The present invention relates to a device for measuring the elasticityof red blood corpuscles (Erythrocytes). Red blood corpuscles are storedunder sterile conditions in plastic bags together with nutrient such asSAG-M solution. In the case at certain conditions of disease red bloodcorpuscles only have to be injected, and to enable injection the qualityof the red blood corpuscles must be known. Hitherto no means has beenavailable for determining the elasticity of the red blood corpuscles andit has just been assumed that after a certain period of storage the redblood corpuscles cannot be used for injection purposes and musttherefore be rejected. It is normally assumed that red blood corpusclescan be stored for about 60 days at a storage temperature of between 4end 6° C. Initially the red blood corpuscles are elastic and mouldablebut become gradually stiffer with time, which means that when theelasticity has fallen to a certain level the rod blood corpuscles can nolonger be injected since this would cause problems in conjunction withinjection.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a device with the aidof which it is possible to determine the elasticity of the red bloodcorpuscles so that the lowest tolerable elasticity can immediately bedetermined. For this purpose two surfaces are used which can be movedtowards and away from each other, one of the surfaces being stationarywhile the other can be moved towards or away from the lower surface. Apackage, e.g. a plastic bag, containing red blood corpuscles andnutrient, the contents being sterile, is placed between the twosurfaces. The movable surface is subjected to a pressure applied thereonso that the surface is continuously under a predetermined pressure. Theweighted surface is subjected to extra pressure pulses with intervalsbetween, whereupon the time is measured for the cell to resume the shapeit had prior to a pressure pulse. This measuring procedure can berepeated and transferred to a computer, with the aid of whichinformation is available as to whether the contents of the bag beingtested is suitable for injecting or not. It has proved suitable for thetwo surfaces to be in the shape of a rectangular plates, one plate beingmovable and the other stationary, the ends of the plates being pivotablyjoined together by means of a suitable hinge construction. The point ofpivot is suitably arranged at a distance from a support surface, whereasthe other and of the lower plate abuts the support surface. A suitableangle for the lower plate in relation to the support surface is in theorder of 45°. With this arrangement also the bag is placed between theplates and the upper plate is subjected to pressure. In this case nodistance can be measured between the two plates and instead the angleprevailing when the red blood corpuscles have been compressed as far aspossible is measured. After which the time is measured from when a pulseceases to when the red blood corpuscles resume their normal shape. Thefrequency of the pressure and variations in the angle are transferred toa control station which records the necessary data to be able to reachan assessment of whether the red blood corpuscles in the blood bag areinjectable or not.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described in more detail with reference tothe accompanying drawing showing one embodiment of the invention.

The drawing shows a test apparatus 1. The apparatus consists of a sidewall 2 and a bottom plate 3, the bottom plate being designed to beplaced on a table. A stationary contact plate is arranged between theside wall and the bottom plate. Above the plate 4 is a movable pressureplate 5, movable at the upper end of the side wall 2 with the aid of asuitable hinge construction 6. In the present case the hingeconstruction is spaced from the upper end of the lower plate. It should,however, be obvious that the hinge 6 can equally well be arranged at theupper end of the plate 4. A suitable angle for the plate 4 in relationto the bottom plate 3 is in the order of 45°. Other suitable angles areof course possible. The movement of the plate 5 is registered by anangle indicator 7. The values are transferred to a control andprocessing means 8. The processing means 8 is connected by a wire 9 toan electromagnetic impulse emitter 11 arranged on a weight 10 placed onthe movable pressure plate 5. A bag containing red blood corpuscles andnutrient is placed between the plates 4 and 5. The contents of the bagis sterile. The impulse emitter 11 may operate continuously at a certainfrequency, or it may emit pulses on desired occasions. All this isachieved by means of the control and processing means 8, which alsoregisters the angle between the two plates 4 and 5. When the plastic bag12 is compressed, the time is measured from pressure to absence ofpressure and represents the time the rod blood corpuscles need to resumetheir naturally elastic original shape.

The advantage of having a stationary contact plate forming an angle withthe bottom plate 3 is that all the red blood corpuscles in the bag 12are then situated as far down in the bag as possible, whereas thenutrient becomes separated as a phase above the red blood corpuscles.

The invention provides a device that ensures that the control andprocessing means 8 advises whether the rod blood corpuscles are in aform suitable for blood transfusion. A security actor has thus beenadded.

What is claimed is:
 1. A device for measuring the elasticity of redblood corpuscles (Erythrocytes), wherein a quantity of blood corpusclesis stored in a package (12) of elastomeric material, preferably ofplastic in the form of a bag, characterized by an upper surface (5) anda lower surface (4) opposite to each other that can be caused toapproach each other under pressure and can be moved apart from eachother, between which said package (12) is placed, and by members (10 and11) generating pressure, and by an arrangement (7) registering therelative movement possible between the two surfaces (4 and 5).
 2. Adevice as claimed in claim 1, characterized in that one end of each ofthe two surfaces (4 and 5) is secured to the other about a transverseshaft (6) so that the surfaces (4 and 5) can be pivoted in relation toeach other.
 3. A device as claimed in claim 2, characterized in that thelower surface (4) is inclined in relation to a support surface (3), theend about which pivoting occurs being located at a distance from thesupport surface (3).